It is commonly believed that highly trained athletes are more susceptible to the reflex responsible for neurally-mediated syncope (fainting) which includes symptoms of lightheadedness and dizziness. There are a number of small mechanistic studies on the physiology of neurally-mediated syncope in the highly trained athlete, although these studies report conflicting results. To date, there are no large studies examining the prevalence of neurally-mediated syncope in highly trained athletes. It is well known that different types of athletic training produce different heart rate, blood pressure and involuntary nervous system effects. Aerobic or endurance training results in increased maximal oxygen consumption and increased resting vagal tone. Resistance, or strength training, does not increase maximal oxygen consumption or enhance resting vagal tone. It has been hypothesized that endurance trained athletes are more susceptible to vaso-vagal syncope, although there are no studies examining this mechanistic hypothesis. It has also been hypothesized that resistance training makes individuals less susceptible to neurally-mediated syncope. Therefore, we propose to study the prevalence of syncope in athletes, and to better understand the pathophysiology of this condition.